Recommended 12au7/5814s for Atma-sphere MP-3

I popped in the Clear tops last night and love them (in this unit), I just bought another pair and Mullard 12au7s from the Blackburn factory - I should be set. I also bought some RCA 6sn7GT - grey glass from the 1940s for the MP-3. Thank you all for your advice. I could not be happier with my Atma-sphere pre and amp; an incredible combination with Merlin speakers (and others I'm sure).

Bill, thanks for jogging my memory - a friend gave me a few of RCA 12AU7 Clear Tops a few years ago to try in this amp, telling me how great they were, and I completely forgot about them. I'll need to give them a shot...

Joe,
Thanks. In response to your first post, earlier this year I purchased 2 pair of the Amperex 7316/ECC186; one pair halo and one pair D getter.

First of all, I didn't need them. My tube inventory has reached a ridiculous number, probably close to 1,000, most of which will never be used. I plan on selling many of these within the next 2 years in order to be at a "manageable" level. Thank goodness most of them were purchased prior to the current "run" on NOS and at really stupid prices e.g. 6922 Bugle Boys for $15/pair and Sylvania 6SN7 Bad Boys for $20/quad etc. Of course this was back in the 70's and 80's.

Secondly, the Amperex tubes are great, perhaps the best iteration of the 12AU7 I've heard. If money isn't important it probably doesn't get any better. However, having heard them in a number of amps and preamps, I would not spend that much money again. There are other 12AU7 that perform admirably for much less.

YMMV

While I understand that to some extent, every tube matters, do the 6sn7s make as noticeable difference in the MP-3 compared with the 12au7s? That is, are these slots worth spending NOS money on?

On the M-60s, do the front and back 6sn7s (V1? V2?)get equal billing for NOS upgrades, or are the V1 spots more sensitive in terms of impacting the sound? Additionally, my understanding is that the V2s in the M-60s in the back have to be GTA/Bs to handle the voltage.

When does the bidding start on the Bad Boys?

I have an MP-1 which does not use the 12AU7 so I cannot compare the relative influence of those tubes with the 6SN7.

In the MP-3 I believe the two sections of each channel's 6SN7 are part of its circlotron output with each cathode in a tube handling one-half of the wave form. (Hopefully Ralph will correct if thats wrong. :-) Thus, it is v. important there be a decent match between the sections within that tube, and that the tube be quiet. As Tvad notes, 'quiet' is a critical attribute - moreso for the preamp than for the amps - so a dealer (such as AndyB at VTS and others) who will screen for noise may save you some money in the long run even if he charges a bit more for the tubes.

The brand/vintage of each channel's 6SN7 will have a real impact on the preamp's sonic character. Some contemporary tubes are 'not bad' - eg., I and others who've tried the Electro-Harmonix 6SN7 find it tends toward a timbre not far from a Sylvania GTB. However, quiet NOS versus a Chinese or Russian 6SN7 in that position, is, imo, not much of a contest and for me NOS are worth the extra rubles. While you can spend a lot of money on the more exotic 6SN7 varietals (bad boy chrome domes, round plate tung-sols,'W's, etc.) a couple nice Ken-Rad, Sylvania, Raytheon, or RCA GTs/VT-231s shouldn't break the bank - especially if you start with used tubes to learn your own sonic preferences. If you haven't seen the head-fi 6SN7 thread, you can read it here.

Fwiw, I've found Herbies tube dampers do their thing nicely on the line stage tubes as well as in the phono section. I use them on 6 out of the 10 6SN7s in the MP-1's line stage, and on 6 of the 8 12AT7s in the phono section. Best of luck tube rolling your new MP-3!

Tim